Utility of Noncontrast Magnetic Resonance Imaging for Detection of Recurrent Vestibular Schwannoma.

BACKGROUND: Gadolinium-enhanced T1-weighted magnetic resonance imaging (MRI) (T1WI) is the conventional imaging technique of choice to detect vestibular schwannoma (VS) recurrence or regrowth, despite suboptimal specificity secondary to enhancing postoperative changes. Furthermore, recent concerns regarding the accumulation of gadolinium in body tissues have led for a call to reduce the number of contrast-enhanced examinations. The objective of the current study is to evaluate the diagnostic accuracy of high-resolution noncontrast (three-dimensional [3D] T2) MRI relative to gadolinium-enhanced T1WI in the detection of VS recurrence after resection. METHODS: Following Institutional Review Board approval, 13 consecutive postoperative patients with VS recurrence or regrowth were identified from a prospectively maintained clinical database in which recurrence was determined by progression on serial postoperative MRI examination. Three blinded neuroradiologists retrospectively evaluated a total of 41 postoperative MRI examinations from these patients using only gadolinium-enhanced T1WI and 3D T2 MRI for recurrence or regrowth. Interobserver agreement, differences in detection between the two sequences, and the sensitivity and specificity of 3D T2 MRI were assessed. RESULTS: Fifteen of the 41 postoperative MRIs demonstrated progression, as determined by examiner consensus on the gadolinium-enhanced T1WI. Agreement, measured using Krippendorff's alpha, was 0.82 for the 3D T2 images and 0.83 for the contrast-enhanced T1WI. All the three examiners demonstrated no difference in the detection of progression between the two sequences (McNemar's test p values 0.69 for examiner 1, 0.63 for examiner 2, and 0.99 for examiner 3). The sensitivity of 3D T2 was 0.78 (CI 0.60-0.96), while the specificity was 0.94 (CI 0.86-1.00). CONCLUSION: Noncontrast high-resolution 3D T2 MRI seems sufficient to assess for recurrence or regrowth after VS resection. The results of this study have implications for reducing cost, time, and adverse events associated with gadolinium administration in this population requiring serial follow-up examinations. These promising, yet preliminary findings warrant confirmation with a larger prospective cohort of patients.